For each additional recommended screening before childbirth, there was a direct increase in absolute PTD risk of 0.073 (95% confidence interval, 0.026-0.120), according to a study led by Rebecca A. Bromley-Dulfano, MS, an MD candidate at Stanford (Calif.) University and a PhD candidate in health policy at Harvard University, Cambridge, Mass.
courtesy Ms. Bromley-Dulfano
Rebecca A. Bromley-Dulfano
There was no significant change in very preterm delivery (VPTD) risk, but mothers with hypertension or diabetes were at higher PTD risk.
Women in this younger age group are more prone to PTD. According to the study’s estimate, an additional 73 PTDs per 100,000 women could be expected for every 1 additional recommended screening before childbirth. For the year 2018, that translated to an estimated 1,348 PTDs that could have been averted, with reduced screening requirements (3% relative reduction).
“If you screen someone for cervical cancer and find a cervical lesion, the possible next steps can include a biopsy and an excisional procedure to remove the lesion,” Ms. Bromley-Dulfano explained, “and these procedures which remove a small (mostly diseased) part of the cervix have been shown to slightly increase the risk of PTD. Particularly in young individuals with a cervix who are known to have high rates of lesion regression and who have more potential childbearing years ahead of them, it is important to weigh the oncological benefits with the adverse birth outcome risks.”
Young women are more likely to have false-positive results on Papanicolaou tests and lesion regression within 2 years but may undergo unnecessary treatment, the authors noted.
Cervical excision procedures have previously been associated in clinical trials with an increase in PTB risk.
In their 2017 decision model in a fictive cohort, for example, Kamphuis and colleagues found the most intensive screening program was associated with an increase in maternal life years of 9%, a decrease in cervical cancer incidence of 67%, and a decrease in cervical cancer deaths of 75%. But those gains came at the cost of 250% more preterm births, compared with the least intensive program.
“These results can be used in future simulation models integrating oncological trade-offs to help ascertain optimal screening strategies,” the researchers wrote.
While the optimal screening strategy must trade off the oncologic benefits of cancer detection against the neonatal harms of overtreatment, the ideal age of cervical cancer screening onset and frequency remain uncertain, the authors noted. Recent American Cancer Society guidelines recommending less frequent screening for some diverge from those of other societies.
“The first and foremost priority is for gynecologists to continue to have individualized conversations with patients about all of the benefits and risks of procedures that patients undergo and to understand the benefits and risks influencing screening guidelines,” Ms. Bromley-Dulfano said.
Cross-sectional study
The study used data from the Centers for Disease Control and Prevention’s National Center for Health Statistics to analyze associations between cervical cancer screening guidelines and birth outcomes women who had a singleton nulliparous birth from 19916 to 2018. Gestational age and maternal characteristics were drawn from birth certificates.
The mean age of the 11,333,151 multiracial cohort of women was 20.9 years, and 6.8% had hypertension or diabetes. The mean number of guideline-recommended screenings by time of childbirth was 2.4. Overall, PTD and very PTD occurred in 1,140,490 individuals (10.1%) and 333,040 (2.9%) of births, respectively.
Those with hypertension or diabetes had a somewhat higher PTD risk: 0.26% (95% CI, 0.11-0.4) versus 0.06% (95% CI, 0.01-0.10; Wald test, P < .001).
courtesy Northwell Health
Dr. Fidel A. Valea
Offering an outsider’s perspective on the analysis, ob.gyn. Fidel A. Valea, MD, director of gynecologic oncology at the Northwell Health Cancer Institute in New Hyde Park, N.Y., urged caution in drawing conclusions from large population analyses such as this.
“This study had over 11 million data points. Often these large numbers will show statistical differences that are not clinically significant,” he said in an interview. He noted that while small studies have shown a possible impact of frequent Pap tests on cervical function, “this is not 100% proven. Research from Texas showed that screening made a difference only in cases of dysplasia.”
Dr. Valea also noted that screening guidelines have already changed over the lengthy time span of the study and do reflect the concerns of the study authors.
“We know that the HPV virus is cleared more readily by young women than older women and so we have made adjustments and test them less frequently and we test them less early.” He added that conservative options are recommended even in the case of dysplasia.
In defense of the Pap smear test, he added: “It has virtually wiped out cervical cancer in the U.S., bringing it from No. 1 to No. 13.” While broadening HPV vaccination programs may impact guidelines in the future, “vaccination is still in its infancy. We have to wait until women have lived long to enough to see an impact.”
As to why this age group is more vulnerable to PTD, Dr. Valea said, “It’s likely multifactorial, with lifestyle and other factors involved.” Although based on U.S. data, the authors said their results may be useful for other public health entities, particularly in countries where cervical cancer is considerably more prevalent.
This work received no specific funding. The authors and Dr. Valea disclosed no competing interests.